The invention concerns a cylindrical cutter comprising one or several helically extending cutting edges for machining wood, wooden materials and plastics as well as a method for its manufacture.
For peripheral milling of wood, wooden materials, plastics and similar materials, rotating tools with several cutting edges are used, including cylindrical cutters with at least one cutting edge that extends helically. The cutting edges have an angular momentum about the axis of the cutter. These cutters have inter alia the advantage that, in comparison to cutters whose cutting edges extend parallel to the cutter axis, they run more smoothly because the cutting edge engagement and the cutting force change do not occur so suddenly.
Primarily, the helix angle λs of the tool is in the range of 0° to 25°. Frequently used are end milling cutters or cylindrical cutters having an angular moment of the cutting edges in accordance with this angle.
According to WO 98/04231, this slant angle (helix angle) is between 40° and 60°, preferably at 45°. EP 0 155 216 discloses 45° as well as 50° to 60°. According to JP 61197116 AA (Abstract) it is also between 40° and 60°.
In case of such helix angles each cutting edge impacts in most applications also once per revolution onto the surface to be processed. This impact causes as a result of the high rotary speed of modern wood processing machines significant noise levels at high frequency in accordance with the rotary speed and number of cutting edges. Moreover, because of this impact a compression of the surface results. This has the effect that the wood, in particular when treated with aqueous media, will swell and subsequently must be post-ground. As a result of the kinematic chip removal principle, partially large-volume chips result that with the entire chip collective must be accelerated to cutting speed and thrown off tangentially. This causes high kinetic energies of the removed chips with diffuse directions of action. Accordingly, for suction removal and dust removal a high energetic and technical expenditure is required. The problem of complete removal of chips and dust has not been resolved to this day in a satisfactory way.
CH-PS 161 618 discloses a cylindrical cutter with a helically extending cutting edge for the cutter spindle of a planing machine. The figure shows that the cutting edge has a helix angle of >60°. A practical application of a cutter spindle designed in this way is not known to the applicant.
Obviously, it is not easy to provide a cylindrical cutter with a large helix angle or high overlap rate of the cutting edge with which high quality cuts can be performed. Also, the manufacture, grinding and regrinding of the cutting edges becomes more and more difficult as the helix angle increases.
It is an object of the invention to provide a cylindrical cutter with a high overlap rate of the helical cutting edges and means for its manufacture with which high quality machining of wood is possible.